Patients with reduced or no kidney capacity are critically dependent on regular haemodialysis or peritoneal dialysis. The dialysis may be done in a hospital dialysis unit, in a clinic away from the hospital, in a self-care centre (with some assistance from the staff), or at home. Special training is needed for self-care or home dialysis.
While some home dialysis patients follow a standard schedule of four to five hours three days a week, some use nocturnal home dialysis where they go on dialysis four to six nights a week for six to eight hours while they sleep. Home dialysis greatly improves the removal of waste products from the body and has been found to improve well-being, to allow for a more liberal diet and to reduce the need for medications. This is mainly attributed to the increased dialysis time allowed by performing the dialysis in the patients' normal surroundings.
Present home haemodialysers (see 2 in FIG. 1) and peritoneal dialysers have several disadvantages. Their designs are based on dialysers for clinical use, which are optimised for speed (typical dialysis duration of 2-4 hours), meaning large artificial kidneys, high blood flow rate, and similarly high dialysate flow rate. The operation and user interface is typically designed for professional clinical personnel, and is too complex for the uneducated home user. In addition, they are dependent on the large-scale water purification plants generally available in clinics.
This means that present home dialysers suffer from the following drawbacks:    1. They are too complex to operate.    2. They are too large to be installed in only very spacious surroundings, and not in small private apartments.    3. They are too heavy to be moved around in the home by enfeebled persons (as many patients are or become), which is relevant if both day-time and nocturnal dialysis is to be available. The weight and size of present dialysers does not allow routinely transportation out of the home, e.g. on vacation.    4. They are not adapted to be used in dialysis with long duration, e.g. 6-8 hours.    5. They are dependent on large flow rates of dialysate and thereby on too large volumes of purified water for the dialysate preparation. Purified water can be provided by micro-purification plants installed in the home or integrated in the haemodialyser, presenting yet another operation issue to the patient. Alternatively, the prefabricated dialysate or purified water can be supplied to the home in containers, which again poses a handling problem for enfeebled persons due to the large volumes.